A Core Data Agent Skill for those who still write a lot of old-fashioned Core Data. While we can use SwiftData, my experience is that many projects still rely on the older framework. I’m one of those and have extensive knowledge on this framework, and even gave a talk on best practices.
That’s why I decided to convert my Core Data articles and my open-source repo, Core Data Best Practices, into a brand new Agent Skill. If you’re unfamiliar with those, I highly recommend reading Agent Skills explained: Replacing AGENTS.md with reusable AI knowledge first.
Open Source: Core Data Agent Skill
The Core Data framework didn’t get many updates over the past few years. While it’s a downside for many, it’s an upside for building a new Agent Skill. Many of its APIs are stable, and best practices haven’t changed for a while. Yet, I’ve still seen many agents making rookie mistakes.
That’s why I’m happy to introduce you to my latest skill: AvdLee/Core-Data-Agent-Skill. It allows developers to debug persistence issues, threading errors, or performance problems. It can guide persistence decisions, help determine when to use view context vs. background context, and support CloudKit integration.
The full skill structure looks as follows:
core-data-expert/
├── SKILL.md # Main skill file with decision trees
└── references/
├── _index.md # Navigation index
├── batch-operations.md # NSBatchInsertRequest, NSBatchDeleteRequest, NSBatchUpdateRequest
├── cloudkit-integration.md # NSPersistentCloudKitContainer, schema design, monitoring
├── fetch-requests.md # Query optimization, NSFetchedResultsController, aggregates
├── glossary.md # Core Data terminology and quick definitions
├── migration.md # Lightweight, staged, and deferred migration strategies
├── model-configuration.md # Constraints, derived attributes, transformables, validation
├── performance.md # Profiling with Instruments, memory management, optimization
├── persistent-history.md # History tracking setup, Observer/Fetcher/Merger/Cleaner
├── project-audit.md # Checklist to discover a project's Core Data setup
├── saving.md # Conditional saving, hasPersistentChanges, save timing
├── stack-setup.md # NSPersistentContainer setup, merge policies, contexts
├── testing.md # In-memory stores, shared models, data generators
└── threading.md # NSManagedObjectID, perform vs performAndWait, concurrency(Note: check out the GitHub repo for the latest version of the structure)
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Part of a larger set of Agent Skills
In case you’ve missed my earlier releases, I’ve also released the following skills:
This combination is highly powerful. One example I like to use on one of my projects looks as follows:
By using all three skills together, I’ve been able to review my feature branch, comparing it to the main branch, and do a final check before merging in. What a time to be alive!
Conclusion
I’m still amazed by the impact Agent Skills have on our daily development workflow. All the skills I’ve released are part of my personal set of skills that I use on a daily basis. I’d love to receive any of your contributions toward a high-value collection that helps us all.
If you want to improve your AI development knowledge, even more, check out the AI Development Category page. Feel free to contact me or tweet me on Twitter if you have any additional tips or feedback.
Thanks!